Method for manufacturing a semiconductor package

ABSTRACT

An apparatus is provided for manufacturing a semiconductor package of the type in which a gap between a semiconductor chip and a mount board is filled with a resin. The apparatus includes resin supply means for supplying the resin along one side of the semiconductor chip, and resin supply control means for controlling the amount of resin supplied by the resin supply means such that more resin is supplied near the central portion of the semiconductor chip than near the end portions of the semiconductor chip. Also provided is a method that includes the steps of connecting the semiconductor chip and the mount board, and supplying the resin along one side of the semiconductor chip in such a manner that more resin is supplied near a central portion of the semiconductor chip than near the end portions of the semiconductor chip. According to the present invention, the resin is supplied such that it is relatively less concentrated near the peripheral portions of the chip so the resin spreads throughout the entire gap at substantially the same time as it flows along the peripheral portion of the chip. Thus, the formation of resin-less voids in the gap is deterred so that the grade and quality of the semiconductor device is improved.

This is a division of application Ser. No. 09/294,955 now U.S. Pat. No.6,191,024, filed Apr. 20, 1999, which is a divisional of applicationSer. No. 08/902,349, filed Jul. 29, 1997 now U.S. Pat. No. 5,935,375,which applications are hereby incorporated by reference in theirentirety.

BACKGROUND OF THE INVENTION

This invention relates to an apparatus and method for manufacturing aflip-chip-type semiconductor package, and more specifically to anapparatus and method for manufacturing a semiconductor package in whichformation of a resin-less void in the gap between the semiconductor chipand a mount board is suppressed, so that the grade and quality of thesemiconductor device is improved.

There has recently been developed a “flip-chip” method for packagingsemiconductor chips. The flip-chip method produces a small semiconductorpackage in which a semiconductor chip is bonded to a mount board.Typically, solder bumps are formed on the electrode pads of thesemiconductor chip, and the solder bumps are connected to the pads andwiring of the mount board. A resin is filled in a gap between thesemiconductor chip and the mount board to secure the package. FIG. 1shows a conventional method for fabricating a semiconductor package thathas a semiconductor chip and a mount board connected in a flip-chipmanner with a resin filled in the gap between the semiconductor chip andthe mount board. As shown, a semiconductor chip 1 is flip-chip-connectedto a mount board 2, and a syringe 4 is moved by means of a drivingmechanism 3 along one side of the semiconductor chip 1 in the directionindicated by the arrow in the figure.

As the syringe is moved along the chip, a resin 5 contained in thesyringe 4 is supplied (for bonding) from the tip of a nozzle 6. Ideally,the resin would gradually enter the gap and would flow from the left tothe right by virtue of a capillary phenomenon until the entire gapbetween the semiconductor chip 1 and mount board 2 was filled with theresin, as shown in FIGS. 2A to 2C. However, the rate at which the resinenters the gap between the chip and mount board is typically lower thanthe rate at which the resin advances around the periphery of thesemiconductor chip. Thus, using the conventional method in which theresin is uniformly supplied by a syringe driven at a constant speed, itis difficult to completely fill the gap between the semiconductor chipand the mount board.

FIGS. 3A to 3C show see-through views of the semiconductor chip toillustrate how the resin typically enters the gap between thesemiconductor chip and mount board when the conventional method is used.Initially, as shown in FIG. 3A, a resin 5 is deposited along one side ofthe semiconductor chip 1. The mount board 2 has a substantially flatsurface and a substantially uniform in-plane temperature distribution,so the resistance to the flow of the resin near the central portion ofthe semiconductor chip is higher than around the peripheral portion ofthe chip. Due to this difference, the rate at which the resin enters thegap is lower than the rate at which the resin advances around theperiphery of the semiconductor chip, as shown in FIG. 3B. Consequently,the resin may fail to completely fill the gap, and instead enclose air(or peripheral atmosphere) so that a void 7 is formed, as shown in FIG.3C. The void 7 lowers the grade and quality of the semiconductor devicebecause it can lead to defects or cracks. More specifically, moistureentering the void can deteriorate the solder bridge, short-circuit thewiring elements on the mount board, or crack the semiconductor device.

As explained above, when the conventional method is used, resin-lessvoids tend to form in the gap between the semiconductor chip and themount board, and thus the grade and quality of the resultantsemiconductor device are lowered.

BRIEF SUMMARY OF THE INVENTION

In view of these problems, it is an object of the present invention toremove the above-mentioned drawbacks and to provide an apparatus andmethod for manufacturing a semiconductor package in which the formationof resin-less voids is deterred so that the grade and quality of thesemiconductor device is improved.

To achieve this object, one preferred embodiment of the presentinvention provides an apparatus for manufacturing a semiconductorpackage of the type in which a gap between a semiconductor chip and amount board is filled with a resin. The apparatus includes resin supplymeans for supplying the resin along one side of the semiconductor chip,and resin supply control means for controlling the amount of resinsupplied by the resin supply means such that more resin is supplied nearthe central portion of the semiconductor chip than near the end portionsof the semiconductor chip. The apparatus supplies the resin such that itis relatively less concentrated near the peripheral portions of thechip, and thus the rate at which the resin flows near the peripheralportions of the chip is reduced. As a result, the formation ofresin-less voids is deterred.

In another preferred embodiment of the present invention, the object isachieved by providing a method for manufacturing a semiconductor packageof the type in which a gap between a semiconductor chip and a mountboard is filled with a resin. The method includes the steps ofconnecting the semiconductor chip and the mount board, and supplying theresin along one side of the semiconductor chip in such a manner thatmore resin is supplied near a central portion of the semiconductor chipthan near the end portions of the semiconductor chip. Accordingly, theresin is supplied such that it is relatively less concentrated near theperipheral portions of the chip. As a result, the formation ofresin-less voids is deterred.

Other objects, features, and advantages of the present invention willbecome apparent from the following detailed description. It should beunderstood, however, that the detailed description and specificexamples, while indicating preferred embodiments of the presentinvention, are given by way of illustration only and variousmodifications may naturally be performed without deviating from thescope of the present invention.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING

FIG. 1 is a view showing a conventional method for manufacturing asemiconductor package;

FIGS. 2A to 2C are views illustrating how the resin should fill the gapbetween the semiconductor chip and the mount board;

FIGS. 3A to 3C are see-through views of the semiconductor chipillustrating how the resin enters the gap in the conventional method;

FIG. 4 is a view showing a method for manufacturing a semiconductorpackage according to a first embodiment of the present invention;

FIGS. 5A to 5C are views illustrating how the resin enters the gapbetween the semiconductor chip and the mount board in the method of FIG.4;

FIGS. 6A to 6C are see-through views of the semiconductor chipillustrating how the resin enters the gap in the method of FIG. 4;

FIGS. 7A and 7B are views showing a multi-nozzle for supplying the resinaccording to a second embodiment of the present invention;

FIGS. 8A and 8B are views showing another multi-nozzle for supplying theresin according to a third embodiment of the present invention;

FIGS. 9A and 9B are views showing a nozzle with an elongated port forsupplying the resin according to a fourth embodiment of the presentinvention;

FIGS. 10A to 10D are views showing a method for manufacturing asemiconductor package according to a fifth embodiment of the presentinvention;

FIG. 11 is a view for explaining capillary pressure in the gap betweenthe semiconductor chip and the mount board; and

FIGS. 12A to 12D are views showing a method for manufacturing asemiconductor package according to a sixth embodiment of the presentinvention.

DETAILED DESCRIPTION OF THE INVENTION

Preferred embodiments of the present invention will be described indetail hereinbelow with reference to the attached drawings.

FIG. 4 shows a method for manufacturing a semiconductor packageaccording to a first embodiment of the present invention. Asemiconductor chip 11 is mounted on a mount board 12 by a flip-chipconnection, and then a driving mechanism 13 moves a syringe 14 along oneside of the semiconductor chip (in the direction indicated by the arrowin the figure). In more detail, the semiconductor chip 11 is providedwith electrode pads that are arranged along the periphery of the chip.Wiring pads are arranged on the surface of the mount board 12 atpositions corresponding to the electrode pads of the semiconductor chip11, and are connected to the electrode pads via metal bumps (e.g.,solder bumps). The wiring pads are led out of the bottom surface of themount board 12 via through-holes and are connected to external pads thatare arranged, for example, in a matrix on the reverse surface of themount board. The mount board is typically formed with materials such asepoxy resin, alumina (Al₂O₃), aluminum nitride (AlN), and/or siliconcarbide (SiC).

As the syringe 14 is moved along the chip, a resin 15 contained in thesyringe is supplied through a nozzle 16 to one end portion of the mountboard. In this embodiment, the amount of resin that is deposited at anypoint along the side of the semiconductor chip is controlled byadjusting the speed of movement of the nozzle 16 along the chip. Inparticular, the flow of resin from the syringe 14 is made constant, andan adjuster 17 controls the driving mechanism 13 to make the nozzle 16move along the end portions of the chip more quickly than it moves alongthe central portion of the chip. Because the amount of resin supplied atany point is proportional to the movement speed of the nozzle 16, theamount of resin that is supplied to the mount board near the endportions of the semiconductor chip is less than is supplied to the mountboard near the central portion of the chip. Thus, the resin 15 isrelatively concentrated near the central portion of the semiconductorchip 11, so the rate at which the resin flows in the gap near theperipheral and side portions of the chip is lower than the rate at whichthe resin flows in the gap near the central portion of the chip. Becausethe resin flows more quickly near the central portion of the chip, theresin entering the gap gradually advances by virtue of the capillaryphenomenon until the gap is completely filled with the resin.

FIGS. 5A to 5C illustrate how the resin completely fills the gap betweenthe semiconductor chip and mount board, with FIGS. 6A to 6C showingsee-through views of the semiconductor chip. As explained above, themovement speed of the syringe is controlled so that a smaller amount ofresin is supplied near the ends of the chip 11. Because the resin isrelatively less concentrated near the peripheral portions of the chip,the rate at which the resin flows near the peripheral portions of thechip is reduced. As a result, the resin 15 spreads throughout the entiregap at substantially the same time as it flows along the peripheralportion of the chip so air (or peripheral atmosphere) is not enclosed inthe gap to form a resin-less void. Thus, a high-grade, high-qualitysemiconductor device is produced.

In the first embodiment of the present invention, the amount of a resinsupplied near the end portions of the semiconductor chip is reduced bychanging the movement speed of the nozzle. In further embodiments,similar advantages can be obtained by changing the configuration of thenozzle or by causing the mount board to have a non-uniform temperaturedistribution. FIGS. 7A and 7B show a multi-nozzle for supplying theresin according to a second embodiment of the present invention. FIG. 7Ais a side view of the nozzle, and FIG. 7B is a sectional view takenalong line VIIB—VIIB of FIG. 7A.

In the second embodiment, a multi-nozzle (i.e., resin supply controlmeans) 21, which is used to supply the resin along one side of thesemiconductor chip, is formed by a nozzle support body 22 and nozzles 23a that are arranged in a row. In more detail, the nozzles 23 a arrangednear the end portions of the semiconductor chip 11 have a relativelysmall inner diameter, and the nozzles 23 b arranged near the centralportion of the chip have a relatively large inner diameter. Because theamount of resin supplied over a period of time increases as the innerdiameter of the nozzle is made larger, the larger-diameter nozzles 23 bcan supply more resin than the smaller-diameter nozzle 23 a in the sametime period. Thus, like the first embodiment, the resin is relativelymore concentrated near the central portion of the chip, and the rate atwhich the resin flows near the peripheral portions of the chip isreduced. Accordingly, the different diameter nozzles minimize thedifference between the rate at which the resin flows near the peripheralportions and the rate at which the resin flows near the central portionof the chip, so that the formation of resin-less voids is deterred.

FIGS. 8A and 8B show a multi-nozzle for supplying the resin according toa third embodiment of the present invention. FIG. 8A is a side view ofthe nozzle, and FIG. 8B is a sectional view taken along line VIIIB—VIIIBof FIG. 8A. In the third embodiment, a multi-nozzle 31, which is used tosupply the resin along one side of the semiconductor chip, includes anozzle support body 32, nozzles 33 with the same diameter arranged in arow, and heaters (resin supply control means) 34. The heaters 34 aarranged near the end portions of the semiconductor chip maintain thecorresponding nozzles 33 at a relatively low temperature, and the heater34 b arranged near the central portion of the chip maintains thecorresponding nozzles 33 at a relatively high temperature.

Because the amount of resin supplied over a period of time isproportional to its viscosity, the higher temperature nozzles can supplymore resin than the lower-temperature nozzles in the same time period.Thus, like the first and second embodiments, the resin is relativelymore concentrated near the central portion of the chip, and the rate atwhich the resin flows near the peripheral portions of the chip isreduced. Accordingly, the non-uniform temperature distribution caused bythe heaters minimizes the difference between the rate at which the resinflows near the peripheral portions and the rate at which the resin flowsnear the central portion of the chip, so that the formation ofresin-less voids is deterred.

FIGS. 9A and 9B show a nozzle for supplying the resin according to afourth embodiment of the present invention. FIG. 9A is a side view ofthe nozzle, and FIG. 9B is a sectional view taken along line IXB—IXB ofFIG. 9A. In the fourth embodiment, an elongated nozzle 41, which is usedto supply the resin along one side of the semiconductor chip, includes anozzle support body 42, and a flat-port single nozzle (resin supplycontrol means) 43. The portions 43 a of the nozzle corresponding to theend portions of the semiconductor chip have a relatively narrow width,and the portion 43 b of the nozzle corresponding to the central portionof the chip has a relatively wide width.

Because the amount of resin supplied over a period of time isproportional to the port width, the wider portion of the nozzle cansupply more resin than the narrower portions 43 a of the nozzle. Thus,like the first to third embodiments, the resin is relatively moreconcentrated near the central portion of the chip, and the rate at whichthe resin flows near the peripheral portions of the chip is reduced.Accordingly, the variable-width elongated nozzle minimizes thedifference between the rate at which the resin flows near the peripheralportions and the rate at which the resin flows near the central portionof the chip, so that the formation of resin-less voids is deterred.

FIGS. 10 to 10D show a method for manufacturing a semiconductor packageaccording to a fifth embodiment of the present invention. FIG. 10A showsa side view of an apparatus used in the fifth embodiment, FIG. 10B showsa top view of a portion of the apparatus of FIG. 10A, FIG. 10C shows thetemperature distribution of the mount board, and FIG. 10D shows thetemperature of the resin on the mount board. In the fifth embodiment,the mount board 12 is placed over a surface formed by a heater block 51(resin supply control means) and radiator plates 52. In particular, theheater block is located beneath the portion of the mount boardcorresponding to the central portion of the semiconductor chip, and theradiator plates are located beneath the portions of the mount boardcorresponding to the end portions of the chip to impart a temperaturedifference between the different portions of the mount board. The heaterblock includes a heater rod 51 a and a peripheral portion 51 b that isillustratively formed of a ferrous metal. The radiator plates 52 aretypically made from a material that radiates a greater amount of heatsuch as copper tungsten, alumina, aluminum nitride, or analuminum/silicon/copper alloy.

Because the temperature of the mount board influences the viscosity ofthe resin, the viscosity of the resin flowing through the gap ispartially varied by controlling the temperature distribution of themount board so that the portions of the mount board corresponding to theend portions of the semiconductor chip are at a lower temperature thanthe portion of the mount board corresponding to a central portion of thechip. In other words, the heat radiation rate of the radiator plates 52is higher than the heat radiation rate of the ferrous metal 51 so thereexists a temperature difference across the mount board (FIG. 10C)).Thus, as the resin is supplied to the mount board (e.g., by amulti-nozzle 55 having a nozzle support body 53 and nozzles 54 with thesame diameter), the viscosity of the resin near the central portion ofthe chip is reduced so that the rate at which the resin flows throughthe gap near the central portion of the chip is higher than the rate atwhich the resin flows near the peripheral portions of the chip (see FIG.10D)). This behavior of the resin can be explained by capillary pressureand pressure loss, which are respectively given by the followingformulas. $\begin{matrix}{P = {- \frac{2T\quad \cos \quad \theta}{H}}} & (1)\end{matrix}$

$\begin{matrix}{\frac{P}{X} = {{- \mu}\quad F\quad \eta}} & (2)\end{matrix}$

In these two equations, P is the capillary pressure, T is the surfacetension, θ is the contact angle, H is the stand-off height, η is theviscosity of the resin, μ is the flow velocity, and F is the flowresistance (see FIG. 11). Accordingly, the combination of the heaterblock and radiator plates allows the resin to completely fill the gap sothat a high-grade, high-quality semiconductor device is produced.

FIGS. 12A to 12D show a method for manufacturing a semiconductor packageaccording to a sixth embodiment of the present invention. FIG. 12A showsa side view of an apparatus used in the sixth embodiment, FIG. 12B showsa top view of a portion of the apparatus of FIG. 12A, FIG. 12C shows thetemperature distribution of the mount board, and FIG. 12D shows thetemperature of the resin on the mount board. In the sixth embodiment,the mount board 12 is placed over the heater block 61 (resin supplycontrol means), and the radiator plates 62 are positioned near theportions of the mount board 12 corresponding to the end portions of thesemiconductor chip. In this embodiment, the radiator plates 62 dissipateheat from nearby portions of the surface of the heater block so thatthere is a gradually changing temperature difference between the portionof the mount board corresponding to the central portion of thesemiconductor chip and the portions of the mount board corresponding tothe end portions of the chip.

Similar to the fifth embodiment, the viscosity of the resin flowingthrough the gap is partially varied by controlling the temperaturedistribution of the mount board so that the portions of the mount boardcorresponding to the end portions of the semiconductor chip are at alower temperature than the portion of the mount board corresponding to acentral portion of the chip. Thus, as the resin is supplied to the mountboard (e.g., by a multi-nozzle 65 having a nozzle support body 63 andnozzles 64 with the same diameter), the viscosity of the resin near thecentral portion of the chip is reduced so that the rate at which theresin flows through the gap near the central portion of the chip ishigher than the rate at which the resin flows near the peripheralportions of the chip (see equations 1 and 2). Accordingly, the heaterblock and adjacent radiator plates allow the resin to completely fillthe gap so that a high-grade, high-quality semiconductor device isproduced.

In the fifth and sixth embodiments described above, a non-uniformtemperature distribution is imparted to the mount board to control theflow of the resin in the gap between the semiconductor chip and themount board. However, in further embodiments of the present invention,similar advantages can be obtained by heating the semiconductor chip sothat is has a temperature higher than the temperature of the mountboard. In one such embodiment, a radiator plate is placed under themount board. Because of the heat radiation effect of the radiator plateand mount board, a temperature difference is imparted between theportion of the mount board corresponding to the central portion of thesemiconductor chip and the portions of the mount board corresponding tothe end portions of the chip. Thus, a similar effect on the flow of theresin in the gap is obtained.

As described above, the present invention provides an apparatus andmethod for manufacturing a semiconductor package in which the formationof resin-less voids is deterred so that the grade and quality of thesemiconductor device is improved.

While there has been illustrated and described what are presentlyconsidered to be the preferred embodiments of the present invention, itwill be understood by those in the art that various other modificationsmay be made, and equivalents may be substituted, without departing fromthe true scope of the invention. Additionally, many modifications may bemade to adapt a particular situation to the teachings of the presentinvention without departing from the central inventive concept describedherein. Therefore, it is intended that the present invention not belimited to the particular embodiments disclosed, but that the inventioninclude all embodiments falling within the scope of the appended claims.

What is claimed is:
 1. A method for manufacturing a semiconductorpackage of the type in which a gap between a semiconductor chip and amount board is filled with a resin, said method comprising the steps of:connecting the semiconductor chip and the mount board; supplying theresin along one side of the semiconductor chip in such a manner thatmore resin is supplied near a central portion of the semiconductor chipthan near the end portions of the semiconductor chip; and wherein thestep of supplying the resin includes imparting a non-uniform temperaturedistribution to one of the semiconductor chip and the mount board, andwherein a portion of the mount board corresponding to the centralportion of the semiconductor chip is maintained at a higher temperaturethan portions of the mount board corresponding to the end portions ofthe semiconductor chip.
 2. The method as defined in claim 1, wherein theresin is controlled to a temperature at which the resin is hard to cure.3. A method for manufacturing a semiconductor package of the type inwhich a gap between a semiconductor chip and a mount board is filledwith a resin, said method comprising the steps of: connecting thesemiconductor chip and the mount board; and supplying the resin alongone side of the semiconductor chip in such a manner that more resin issupplied near a central portion of the semiconductor chip than near theend portions of the semiconductor chip, wherein the step of supplyingthe resin includes imparting a non-uniform temperature distribution toone of the semiconductor chip and the mount board; and wherein thecentral portion of the semiconductor chip is maintained at a highertemperature than the end portions of the semiconductor chip.
 4. Themethod as defined in claim 3, wherein the resin is controlled to atemperature at which the resin is hard to cure.
 5. A method formanufacturing a semiconductor package of the type in which a gap betweena semiconductor chip and a mount board is filled with a resin, themethod comprising: connecting the semiconductor chip and the mountboard; and supplying the resin along one side of the semiconductor chipin such a manner that more resin is supplied near a central portion ofthe semiconductor chip than near the end portions of the semiconductorchip, wherein supplying the resin includes supplying the resin through aplurality of nozzles, the nozzles are arranged in a row along the oneside of the semiconductor chip, and the nozzles located near the centralportion of the semiconductor chip are maintained at a higher temperaturethan the nozzles located near the end portions of the semiconductorchip, and the resin is controlled to a temperature at which the resin ishard to cure.